Propagated Vasodilation in the Microcirculation of the Hamster Cheek Pouch

Propagated vasodilation has been observed in the peripheral vasculature and may be significant in integrating the behavior of terminal arterioles and larger vessels. We have studied the characteristics of propagated vasodilation induced by acetylcholine in the microcirculation of the cheek pouch of the golden hamster. The technique of microionophoresis was used as a means of achieving relatively precise temporal and spatial application of drugs to single arterioles. Application of acetylcholine to an arteriole usually resulted in vasodilation which spread rapidly upstream and downstream from the point of application at a rate much greater than could be accounted for by diffusion or by other means of movement of the agent. Longitudinal propagation velocities for a series of arterioles 20 to 40μ in diameter averaged 0.02 cm/sec. The propagated response was relatively specific, being induced by acetylcholine but not by histamine, K+, H+, or eledoisin. The response was graded in both extent and magnitude, was propagated bidirectionally from the point of origin, was observed in vessels as small as 15μ o.d., and could be blocked by lidocaine.